Ta có:

\(74\frac{19}{35}.\frac{7}{90}+15\frac{16}{35}:\frac{90}{7}\)

\(=74\frac{19}{35}.\frac{7}{90}+15\frac{16}{35}.\frac{7}{90}\)

\(=\frac{7}{90}.\left(74\frac{19}{35}+15\frac{16}{35}\right)\)

\(=\frac{7}{90}.90\)

\(=7\)

\(74\frac{19}{35}.\frac{7}{90}+15\frac{16}{35}.\frac{7}{90}\)

\(\frac{7}{90}.\left(74\frac{19}{35}+15\frac{16}{35}\right)\)

\(\frac{7}{90}.90\)

\(7\)

a) \(74\frac{19}{35}.\frac{7}{90}+15\frac{16}{35}.\frac{7}{90}+2\frac{14}{90}\)

= \(\left(74\frac{19}{35}+15\frac{16}{35}\right).\frac{7}{90}+2\frac{14}{90}\)

=  90 . 7/90 + 194/90

= 630/90 + 194/90

= 824/90 = 412/45

b) (-2/5 + 3/7) - (4/9 + 12/20 - 13/35) + 7/35

= -2/5 + 3/7 - 4/9 -  3/5 + 13/35 + 7/35

= (-2/5 - 3/5) + 3/7 - 4/9 + (13/35 + 7/35)

= -1 + 3/7 - 4/9 + 4/7

= -1 + (3/7 + 4/7) - 4/9

= -1 + 1 - 4/9 = -4/9

mik đang cần rất gấp , giúp mik vs !! 

a. 35.34 + 35.86 + 65.75 + 65.45

= 35.(34 + 86) + 65.(75 + 45)

= 35.120 + 65.120

= 120.(35 + 65)

= 120.100

= 12000

b. 21.7² - 11.7² + 90.7² + 49.1258.16

= 21.7² - 11.7² + 90.7² + 7².1258.16

= 7².(21 - 11 + 90 + 1258.16)

= 7².20228

= ... (Không tính nhanh được :3).

a. 35.34 + 35.86 + 65.75 + 65.45

= 35.(34 + 86) + 65.(75 + 45)

= 35.120 + 65.120

= 120.(35 + 65)

= 120.100

= 12000

b. 21.7² - 11.7² + 90.7² + 49.1258.16

= 21.7² - 11.7² + 90.7² + 7².1258.16

= 7².(21 - 11 + 90 + 1258.16)

= 7².20228

= ... (Không tính nhanh được :3).

 1)=133\18

2)=171\5

3)=9\7

4)=431\160

ban tra loi ki cho mk nhe

a, \(35\times34+35\times86+65\times75+65\times45\)

\(=35\times(34+86)+65\times(75+45)\)

\(=35\times120+65\times120\)

\(=(35+65)\times120=100\times120=12000\)

b, \(21\times7^2-11\times7^2+90\times7^2+49\times125\times16\)

Làm nốt

a)35 x 34 + 35x 86 + 65 x 75 + 65 x 45

=35 x (34+86) + 65 x (75 + 45)

=35 x 120 + 65 x 120

=120 x (35 + 65)

=120 x 100

=12000

Chúc học tốt!